Access is a great program as a stand-alone, but sometimes you may need to use an Access table in another program. For instance, maybe your boss wants a copy of a mailing list so he can make some cuts in it, but he's a die-hard Excel user with no interest in learning Access. You can give him the table in Excel format, and then when he's finished with it, you can import it back into an Access table.
Or perhaps you have used a different database program, like dBase or FoxPro, and now you want to convert your databases over to Access. You can import the data, and save it in Access format.